Explore the Gemstore

October

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oct gems

Opals and Tourmalines


Opals


Opal is one of the worlds most coveted gemstones. Its name of all from the Roman opalus, drive from the Greek opallios, meaning “to see a change of color”. The Greek word was a modification of the ancient Indian Sanskrit name for opal, upala, which meant “precious stone.” If one spoke in mixed tongues, then opal would be opallios upala, “to see a change of color precious stone.”

 


Just the facts


Opals possess flashes of rainbow colors that change with the angle of observation, called play of color. This affect this effect is similar to the rainbow colors displayed on a soap bubble, only much more dramatic. This should not be confused with opalescence, which is the milky-blue or pearly appearance of opal caused by the scattering of light.

 


 Opals Include:

Black, Boulder, Ethiopian, Fire, Green, Jelly, Peruvian, Semi- Black, White


Opal

October's Birthstone

Major Sources

Australia, Brazil, Ethiopia, Mexico, Peru, South Africa, Tanzania, USA & Zimbabwe

Colors Found

 Various

Family

Opal: SiO2 + H2O

Hardness

5.5 – 6.5

Refractive Index

1.37 – 1.52; SR

Specific Gravity

1.98 – 2.50

Crystal System

Amorphous

Tourmalines


Tourmaline boasts a colorful and romantic history, rivaling all but the most unique gems. It is found in an incredible array of gorgeous colors. Coming in a pallet of over a hundred different hues, the tourmaline is one of the world’s most diverse gemstones. This has resulted in the nickname the chameleon gem, which is doubly appropriate when you consider that one major source of tourmaline is Madagascar, home to more than half of the world’s chameleon species.


Just the Facts


While tourmalines occur in large crystal sizes, gems of sufficent beauty to be set into jewelry are not available in great abundance. Because of their sizes, crystals are sometimes cut into long rectangular shapes following the axis of the crystal.

 


Tourmalines Include:

Green, Indicolite, Bi-Color, Paraiba, Rubellite


Tourmaline

October's Birthstone

Major Sources

Afghanistan, Brazil, Kenya, Madagascar, Mozambique, Nigeria, Sri Lanka, Tanzania, USA & Zambia

Colors Found

 Various

Family

Tourmaline: Complex borosilicate

Hardness

7 – 7.5

Refractive Index

1.61 – 1.66; SR

Specific Gravity

2.82 – 3.32

Crystal System

Trigonal

 

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